Wide angle illuminating fixture



April 17, 1956 G. A. BRONSON ET AL 2,742,564

WIDE ANGLE ILLUMINATING FIXTURE Filed Feb. 25, 1952 United vStates O ,A

WIDE ANGLE nun/mst'Arlt-sr; FIxr'Ua-a George A. Bronson, Santa Monica,and Harlan EPltcher,

Los'Angeles, Calif., assignorstolDouglasAh-craft Cornv pany, Inc.; SantaMonica, Calif.- Y l Y Application February 23, Serial No. 273,056 'Y g 1claim. (ci. zito- 7,71 j. a f j linvention relates Y toA lightingfixtures, {partici-1larly those forindicating the position or attitudeof vehicles carrying same.

It is an object of the invention to Iprnvide surface of theA lens ofthevfixturev and occupying 360cr f i arc in a plane substantiallyyparallel to the adjacent surface of the vehicle. Since theoutermost-surface ofthe fixture,

which ,s'urfaciis the. exterior? surface of; the lcnsgprotrudes verylittlefrom the adjacentfsurfac'e of the vehicle, the amount of frangiblematerial exposed to danger of damaging impact is reduced to the minimum.

Another object of the invention is to provide a fixture of this typewhich, by means of a unirefrangent lens having opposed spherical facesthe inner one of which s concentric with the light source and thereforejeffects no refraction of the light rays entering same from the lightsource, will be' ableA to illuminate a regionl extending from edge toedge vertically voutwardly of the carrying surface and 360 aroundthefxture'withoutzthe use of compound lens-surfaces, or tort orjwarpedrefractive surfaces. By these means, the cost of making the lens and therest of the fixture is reduced considerably bewing'carrying one 0f thepresent `fixtures mounted sub,

v '"fhe housing 1K5 is ofa kgenerally vheniispherivcral"'shape forcompactness and ease of fabrication. The one por-A .ftion, 27, of thewall of the body is planeal and extends stantially flush with its uppersurface; and

. lFigure 2r isa section on line 2-2 of Figure 1.

uThe construction shown in the drawings comprises an Yillumination=unit, or wing tip light, 10, snnkfin an opening.l'l'provided in an airplane wing-tip skin 12.-- The inner: edge Yof theopening'is encircled by an annular flange 13,; onwhichrests thecomplementaryannual flange '14;of. lthe l body 15 fofthe:lighting1xture.

the :outer edge of flange 14 is'an annular support-rim '16.

- Afclamping vring 17',A annularly rabbetedzas shown at-181 l and `19 toprovide annular clamping shoulders at itslinner,

andzouter* peripheries, :is -vseated' by means of the outerrabbetflfon'the r'im 16;4 VThe inner' clamping shoulder provided'bythel-rabbet 19 of the clamping ring engages inian annular groove 21 onthe upper outer peripher'y of the outermost face: of @the lens.; Packingl41 maybe.

interposed as shown. The clampingY ring is heldinits engagement with thelens, to maintain the latter in place, by means of, fasteners 22, suchas self-tapping'screws which r'thread' into'the annular rings Yorflanges. 13 and` 14at the yopening in the wings skin."

A lens support, or retainer ring 24, here shown asza;

concave-convex' metallic annulus or open-center plate, Ais

t providedl for the purpose of supporting theglens-iagainst?theLinwardpull of the fasteners.

Figure 1v the 'inner periphery'of retainer ringv 24 is pro-.

vided withfazplurality of radially 'inwardly extending ears 42,1o`cated120, apart peripherally, no ear therefore beingv disposed at theilampside of the fixture, in order notlto interfere with the, lamp housing.The ,rt'ain'er ring is held to zthelclamping ring. and Vagainst vthe,lens'lby meansVv of plurality of fasteners ZSKthe'headsa of whichengage ears,

26 extending radially outwardly from the outer periphery ofthe retainer.',sp f

at an obtuse angleto the bottom of the housing. In said portion is anaperture 28 through which passes a member 29 abutted against the outersurface of wall 27 by meansv of an'annular'shoulder 31. A retaining ring32,`ins`erted in' an annular groove 33, on the inner low that of aconventional such fixture of the same size and candlepower, since theentire lens can be cast, instead of requiring expensive grinding orother extra working of at least the outer surfaceof the lens to providea relfractive surface to correct the refraction effected at theconventionalfinner surface ofthe lordinary* such lens and bend thelightthrough 180i, edge-to-oppositeedge, of the Y outer lens surface. f

The other objects and advantages ofthe invention will 'either becomeapparent'or be made manifest as this disclosure progresses.

One of the presently-preferred embodiments of 'these and otherinventiveconcepts is illustrated, by way of example only, in theaccompanying drawingsrand will be described hereinafter in conjunctiontherewith. Although i the invention is shown and described as embodiedin an airplane asy a wing-mounted position indicating light, it

will become apparent hereinafter that the invention is equally welladapted for employment in othervehicles end portion of the socket,cooperatesfwith the shoulder 31 to maintain member 29 in place. yMountedcoaxially of member`29 is an electrical socket member 34 terminating atthe outer end portion of member 29 in a pair of contact prongs 35adapted for coaction with the plug fof an electrical lamp-energizingcircuit, not shown. Member 34 bears' the usual spring contact 36for anelectric lamp or bulb 37 Amounted coaxially therein. The outer end ofthe socket is seized by annular peening 38. The

lamp 37 is so constructed and mounted in the socket toY yextend acrossthe vertical center line of the housing 15. The flens component of thefixture consists of an outwardly light-diverging,`unirefrangent article39 which has no compound, warped, `tort or rectilinear refractivesurfaces.' Instead, both the rinner surface 44rwhich 'does not refract,and the sole refractive surface, which is outerY surface 45, are simple,continuous uninterrupted surfaces which here are exemplified as portionsof the surfaces of spheres. vAs shown, the light-diverging,unirefrangent lens assumes the form -of a concavo-convex, doublemeniscus lens, and an important feature of the invention is V,that theconcavesurface 44 confronts the optical center of the lamp equidistantlyat substantially all points of ythe surface.` As shown, the innersurface is a substantial portion of the surface of a sphere the centerof which lies at the center 49 of the lamps filament. Thus all the raysfrom the latter strike surface 44 at right angles to the tangentsthereto, instead of impinging on said surface Patented Apr. 17, 19561.

Upstandingfl fromA As shown in `plan in.

obliquely. Hence, no refraction occurs as the light passes into the bodyof the lens from the air inside the housing.

Thus, no refraction has to be corrected as the light passes from theinner surface 44 to surface 45 or from the lens outer surface 45 to theair, where occurs the only re-v fraction undergone in the lens. t fSince the preferred form of lens is composed of ,P-yrex glass with arelatively high index of refraction, thereby deflecting peripheral raysto horizontal, and since thev lens is unirefrangent with the lightsource located at the geometrical center of the inner surface 44, theouter face of the lens can be made to consist of a portion of thesurface of a sphere of relatively large radius not concentric withsurface 44. The expensive grinding, and other maching operationsincident to the conventional use of warped, tort or other compoundsurfaces for'the surface 45 are hence obviated, yet the rays from the`light source are directed outwardly from surface 45 through an arc of180, that is the emitted light extends around from horizon to horizon,as it were. It is also emitted all around the 360 periphery of the outersurface. Y i

`Since thus the outer surface 45 can be made almost planeal, it does notprotrude substantially from the adjacent surface of the supportingstructure. Drag and liability of damage by impact are thus reduced to aminimum because of its smoothness and very slight pro-y housing" havingVa yconformation adapting it to t inside Vanopening through asubstantially at supporting structure with its open face directedoutwardly of said opening, the open face of saidC housing beingperipherally bounded by an outwardly angled, upstanding ange; a cuppedsupport ring having its outer lateral periphery attached to the bottomsurface of said supporting structure around the edge of said opening andhaving its inner edg'eannularly engaging the bottom of said flange and`supporting said housing; an outwardly refractive dispersing lens,convexgoutwardly and concave inwardly, disposed concentrically of saidopening; a clamping ring mounted ,on the upper edge of said upstandingange,

` said clamping ring engaging'said lens and extending concentricallyoutwardly thereofgan annular lens support disposed peripherally of theinner face of said lens and attached to said clamping ring; means forattaching said clamping ring to said housing; a socket mounted in saidhousing; and a -lamp with `a small light source inserted in saidsocket-with thecenter of its light source concentric with the center ofcurvature of the concave inward f aceof said lens.

References Cited in the tile of this patent "UNITED STATES PATENTS960,926 yHoops June 7, 1,793,227 V4Evans` Feb. 17, 1931 1,922,618Dickson s--- Aug. 15, 1933 2,146,662 Van Albada Feb. 7, 1939 2,172,248Kost ..-e Sept. 5, 1939 2,257,127 l Roper.r Sept. 30, 1941 2,316,835 r,Blood Apr. 20, 1943 2,373,815 yDel Riccio Apr. 17, 1945 a .t FOREIGNPATENTS 362,649 Great Britain Dec. l0, 1931 514,949 Great Britain Nov.22, 1939

